Facilitating communications between a radio device and a terminal

ABSTRACT

A communication device for use in connecting a mobile station to a terminal includes a first group of frame memories that correspond to radio links used to transmit data to the mobile station. The first group of frame memories is configured to store point-to-point (PPP) frames. The communication device also includes one or more radio converters that convert the PPP frames stored in the first group of frame memories into radio frames. The communication device may further include a second group of frame memories configured to store radio frames received from the mobile station via radio links. The communication device may also include a PPP converter configured to convert the radio frames stored in the second group of frame memories into PPP frames.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.09/901,663 filed Jul. 11, 2001 now U.S. Pat. No. 6,982,963, thedisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to a communication system for use in carrying outcommunication between a mobile terminal or station and an IP packetterminal located within a connectionless network. Herein, it is to benoted that the mobile terminal is operable in accordance with theDigital cellular method and the IP (internet protocol) while the IPpacket terminal carries out communication by the use of a packet.

With recent world wide spread of an internet and a mobile communicationnetwork, attention has been directed to a communication system forinterconnection between an IP (internet protocol) network and the mobilecommunication network. The mobile communication network may include amobile station (MS) and a base station (BS)/a mobile switching center(MSC)/an IWF (interworking function). The BS, the MSC, and the IWF maybe collectively called an interworking facility.

In this event, the mobile station (MS) which is used in such acommunication system may be operable in accordance with the Digitalcellular method (interim standard) protocol prescribed by TIA(Telecommunication Industry Association)/EIA (Electronic IndustryAssociation). Moreover, the mobile station (MS) is also operable inaccordance with the IP (Internet Protocol). In this connection, aprotocol of the mobile station is specified by a hiearchical structurewhich includes a relay layer, a link layer, a network layer, and anapplication layer. Specifically, the relay layer is formed by a Digitalcellular method layer and a radio link protocol (RLP) layer defined bythe Digital cellular method while the link layer is formed by apoint-to-point protocol (PPP) layer. Moreover, the network layer isformed by a TCP (Transmission Control Protocol)/IP (Internet Protocol)layer.

On the other hand, the interworking facility, such as the base station(BS)/the mobile switching center (MSC)/the interworking function (IWF)is located between the mobile station (MS) and the IP network which is aconnectionless network. The interworking facility has a protocolcomposed of the Digital cellular method layer and the RLP layer for themobile station and a protocol composed of a physical (PHY) layer, a PPPlayer, and an IP layer for the IP network.

At any rate, both the mobile station (MS) and the interworking facilityare operable in accordance with the RLP prescribed by the Digitalcellular method, as mentioned before.

Herein, it is to be noted that so called a high speed packet is definedas a service option 22, 23, 24, and 25 in the IS-95B and IS-707A amongthe Digital cellular method, so as to realize a connection between amobile station and the IP network in accordance with the IP protocol.

In addition, it is to be considered that the transmission rate in themobile communication system is very slow in comparison with the IPnetwork because complex procedures should be executed so as to establishor release a connection and an overhead indispensably occurs toguarantee a radio quality. Taking this into account, the above-mentionedprotocol IS-707A includes a RLP version 2 which is defined in connectionwith the high speed packet (mentioned above) in order to raise atransmission rate in communication with a mobile station. According tothe RLP version 2, a plurality of radio channels are multiplexed betweena mobile station and an interworking facility so as to improvetransmission efficiency and to expand an available bandwidth. Morespecifically, the radio channels are simultaneously established inparallel between the mobile station and the interworking facility in theRLP version 2 and include, for example, a fundamental channel and firstthrough eighth supplemental channels. The plurality of the radiochannels are bundled to be subjected to multiprocessing and to expandthe available bandwidth.

It is noted that the radio protocol, such as the RLP version 2, neverrecognizes, for example, a PPP frame, an IP protocol packet, and thelike that belong to an upper layer and that the PPP frame and IPprotocol packet are therefore transparently transmitted in accordancewith the radio protocol.

Thus, neither consideration is made at all in the radio protocol aboutthe PPP frame on multiprocessing the links nor definition is included inthe upper protocol about multiplexing each radio link. Herein, a PPPlink control frame, such as an end request frame, an echo request frame,should be transmitted as the PPP frame. On transmitting such a controlframe in accordance with the radio protocol, the control frame is mixedwith the other PPP frames for user data and multiplexed into radiochannels. Such a mix of the control frame and the data frames makes itdifficult to quickly detect the control frame on a reception side.

In other words, no guarantee is given about transmitting the controlframe defined by the PPP protocol to a reception side, without anyadverse influence to other radio channels. For example, let a sequenceof PPP frames which includes a specific PPP frame be received by theinterworking facility, such as BS/MSC/IWF, and transmitted through aplurality of radio channels to a mobile station in accordance with theradio protocol. The specific PPP frame may be, for example, a PPPLCP(link control protocol) echo request frame. In this event, each of thePPP frames is divided into the plurality of the radio channels. Thismeans that the specific PPP frame is also dispersed or distributed intothe plurality of the radio channels and is transmitted in the form ofRLP frames to the mobile station.

In this connection, the mobile station should detect the specific PPPframe by decoding the RLP frames sent through the plurality of the radiochannels. Such decoding requires complex control processing andcomplicated protocol processing over the plurality of the radiochannels. In addition, a long time is required to execute such complexprocessing and transmission efficiency is reduced.

SUMMARY OF THE INVENTION

An aspect consistent with principles of the invention provides acommunication system which is capable of improving transmissionefficiency by dispensing with complex processing.

Another aspect consistent with principles of the invention provides acommunication system of the type described, which can remove a delayresulting from complex protocol processing.

A further aspect consistent with principles of the invention provides amethod which can effectively process and quickly transmit a controlframe defined by the PPP.

To this end, this invention controls radio channels to carry outmultiplexing transmission in a communication system which may be calleda packet communication system. The communication system is operable inaccordance with the Digital cellular method to carry out communicationbetween a mobile station and an IP terminal included in a connectionlessnetwork.

A communication system according to an aspect of this inventioncomprises a mobile station operable in accordance with a predeterminedmobile communication protocol and an internet protocol (IP) terminaloperable in accordance with an IP. The predetermined mobilecommunication protocol allows use of a plurality of radio links betweenthe mobile station and the IP terminal while the mobile station iscommunicable with the IP terminal. The communication system comprises aninterworking apparatus which is operable in response to an IP framedefined by the IP and a plurality of radio frames defined by thepredetermined mobile communication protocol. The interworking apparatuscomprises framing means for framing each IP frame into PPP framesdefined by the PPP, transmitting frame memory means which are assignedto the radio links, respectively, for storing the PPP frames one by one,respectively, and transmitting means for transmitting the stored PPPframes through the plurality of the radio links in the form of the radioframes, respectively.

The transmitting means may comprise converting means for converting thePPP frames stored in the frame memories into a plurality of radio linkprotocol (RLP) frames and radio frame memory means which are made tocorrespond to the radio links, respectively, for individually storingeach of the RLP frames to make the transmitting means transmit each RLPframe as each of the radio frames.

In addition, the interworking apparatus may further comprise receivingmeans for receiving the plurality of the radio frames through theplurality of the radio links, respectively, reception frame memory meansfor individually storing the radio frames at every one of the radioframes, and reproducing means for reproducing the radio frames intocorresponding PPP frames.

Furthermore, the interworking apparatus further comprises sending meansfor sending the PPP frames to the IP terminal after the PPP frames areconverted into IP frames, when the reproduced PPP frames are IP frames.

In this event, the transmitting frame memory means may comprise aplurality of frame memories which are equal in number to the radio linksassigned to the interworking apparatus. The interworking apparatusfurther comprises reception frame control means for assigning the PPPframes sent from the framing means to the respective frame memories andtransmission frame control means for successively reading the radioframes out of the reception frame memory means.

The number of the plurality of the frame memories of the transmittingframe memory means is changed with reference to the number of the radiolinks.

An interworking apparatus to which this invention is applicable islocated between a mobile station and an IP terminal so as to carry outmutual conversion between Digital cellular method and the IP protocol.The mobile station is operable in accordance with both the Digitalcellular method and the IP protocol while the IP terminal is operable inaccordance with the IP protocol. According to another aspect of thisinvention, the interworking apparatus comprises an IP protocol interfacefor executing interface processing of the IP protocol to produce IPframes, a radio protocol interface for executing interface processing ofa radio protocol to produce radio frames, a framing portion responsiveto the IP frames, for framing the IP frames into PPP frames, a receptionframe control portion for assigning the respective IP frames at everyone of radio links, PPP frame memory means for individually storing thePPP frames at every one of the radio links determined in number undercontrol of the reception frame control portion, RLP converting means forconverting the PPP frames stored in the frame memories into RLP framesequal in number to the PPP frames, frame transmitting means which aremade to correspond to the RLP converting means for transmitting the RLPframes through the radio interface to a radio transmission path, radioreception means for receiving, through the radio interface, RLP framessent from the radio links determined in number, RLP frame memory means,the number of which is determined in accordance with the radio links,for successively storing each of the RLP frames, a transmission framecontrol portion for successively reading the RLP frames out of the RLPframe memory means, reproducing means for reproducing the RLP framesread out of the RLP frame memory means into corresponding PPP frames, toconvert the PPP frames into the IP packets on detection of the IP frame.

In this event, the mobile station negotiates with the radio interfaceprior to communication with the interworking apparatus, in connectionwith the number of the radio links in a forward direction from theinterworking apparatus to the mobile station and in a reverse directionfrom the mobile station to the interworking apparatus. Under thecircumstances, the radio interface informs the reception frame controlportion and the transmission frame control portion of the agreed numberof the radio links obtained as a result of the negotiation. In addition,the numbers of the PPP frame memory means and the RLP frame memory meansare determined in response to the agreed number of the radio links.

According to another aspect of this invention, a mobile stationcomprises the interworking apparatus mentioned above.

According to yet another aspect of this invention, an interworkingapparatus is for use in carrying out conversion of Digital cellularmethod and IP protocol so as to mutually connect between a mobilestation and an IP terminal. The interworking apparatus comprises an IPprotocol interface for carrying out IP protocol interface processing toproduce IP packets, an radio interface for carrying out radio protocolinterface processing, a framing portion responsive to the IP packetssent from the IP protocol interface for framing the IP packets into PPPframes, a reception frame control portion for assigning the PPP framesframed by the framing portion at every one of radio links, a pluralityof PPP frame memories for storing the PPP frames sent from the framingportion, at every one of the radio links, a plurality of RLP convertingportions, which correspond to the respective PPP frame memories, forconverting the PPP frames read out of the PPP frame memories into RLPframes, respectively, a plurality of frame transmission portions, whichcorrespond to the respective RLP converting means, for transmitting theRLP frames sent from the RLP converting means to radio transmissionpaths through the radio interface, a plurality of frame receptionportions, supplied with RLP frames sent through the radio links, fordistributing the RLP frames at every one of radio links, a plurality ofRLP frame memories for successively storing the RLP frames sent from theframe reception portions, a transmission frame control portion forsuccessively reading the RLP frames out of the RLP frame memories, areproducing portion for reproducing the RLP frames read out of the RLPframe memories into PPP frames to supply IP packets to the IP protocolinterface by converting the PPP frames into the IP packets on detectionof the IP protocol frames. The reception frame control portion and thetransmission frame control portion are given the numbers of the radiolinks which are determined in relation to a forward direction from theinterworking apparatus to the mobile station and a reverse directionfrom the mobile station to the interworking apparatus. The reception andthe transmission frame control portions vary available numbers of thePPP frame memories and the RLP frame memories with reference to thenumbers of the radio links.

In this case, the transmission frame control portion processes framesread out of the RLP frame memories when the frames read out of the RLPframe memories are PPP link control frames.

According to still another aspect of this invention, a communicationsystem is for use in connecting a mobile station through an interworkingapparatus to a packet terminal included in a connectionless network. Theinterworking apparatus comprises a first group of frame memories forstoring PPP frames produced from reception packets at every one of radiolinks, means for reading the PPP frames read out of the first group ofthe frame memories to convert the PPP frames into radio frames and toproduce the radio frames through the radio links, respectively, a secondgroup of frame memories for storing radio frames sent through radiolinks at every one of the radio frames, and reproducing means forreproducing the radio frames read out of the second group of the framememories into PPP frames.

According to another aspect of this invention, a method is for use inestablishing a connection between a mobile station and a terminal of aconnectionless network through an interworking apparatus. The methodcomprises the steps of providing multiplexed radio links between themobile station and the interworking apparatus, successively storingradio frames sent through the radio links in those RLP frame memories ofthe interworking apparatus which are determined for every one of theradio links, successively reproducing the radio frames into PPP frames,and delivering PPP frames sent from the terminal to PPP frame memorieslocated at every one of the radio links to convert the PPP frames intoradio frames and to produce the radio frames through the radio links,respectively.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagram for use in describing a protocol stack used in acommunication system;

FIG. 2 is a block diagram of a packet communication system to which thisinvention is applicable;

FIG. 3 is a view for use in describing a radio link control operation;

FIG. 4 is a view for use in describing the radio link control operationin detail;

FIG. 5 is a block diagram of a communication system according to apreferred embodiment of this invention; and

FIG. 6 is a block diagram of an interworking apparatus used in thecommunication system illustrated in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 through 4, description will be made about acommunication system to which this invention is applicable, for a betterunderstanding of this invention. As shown in FIG. 1, the communicationsystem has an IP network and a mobile communication network which isinterconnected to the IP network and which may be operable in accordancewith the Digital cellular method. The illustrated IP network isspecified by a router and a host while the mobile communication networkis specified by a mobile station (MS) and BS/MSC/IWF, as mentionedbefore. In FIG. 1, illustration is made of protocols which have layerstructures. Specifically, each protocol of the router and the host inthe IP network has a physical layer (PHY), a link layer (LINK), and anetwork layer of TCP/IP. The protocol of the host has also anapplication layer (APL) as an uppermost layer.

On the other hand, the protocol of the illustrated mobile station (MS)is specified by a combination of a lower protocol defined by the TIA(Telecommunications Industry Association)/EIA (Electronic IndustryAssociation)/Digital cellular method and an upper protocol defined bythe IP protocol, such as PPP, TCP/IP. The lower protocol is composed ofthe Digital cellular method related to CDMA and the radio link protocol(RLP).

The BS/MSC/IWF which is placed between the IP network and the MS has theprotocols of the physical layer (PHY), the link layer (LINK), and the IPlayer on the IP network side and the protocols of the Digital cellularmethod and the RLP on the MS side.

In FIG. 2, a communication system is illustrated which can carry outcommunication between a connection oriented network and a connectionlessnetwork. The connectionless network is assumed to be operated incompliance with the IS-95B and IS-707A. More specifically, it is alsosurmised that the connectionless network uses a high speed packetprescribed as the service option in 22, 23, 24, and 25 and carries outcommunication through an interworking apparatus.

Furthermore, the illustrated communication system has the connectionoriented network formed by a plurality of mobile stations 10 ₁ to 10 ₃,a mobile communication network 20, and a radio end terminal or aninterworking facility 40, such as BS/MSC/IWF. The mobile station 10 ₁ to10 ₃ are operable in accordance with both the above-mentioned RLP of theDigital cellular method and the IP protocol while the radio end terminal40 is operable as a protocol end of a radio region. As mentioned before,the radio end terminal 40 can transmit the high speed packet incompliance with the IP protocol and the IS-707A.

As shown in FIG. 2, the connection oriented network is connected to theconnectionless network which includes a part of the radio end terminal40, the IP network 50 and a plurality of the IP terminals 60 ₁ and 60 ₂.The IP network 50 is connected to both the radio end terminal 40 and theIP terminals 60 ₁ and 60 ₂.

In the illustrated example, a sequence of user data is generated by eachIP terminal 60 ₁ and 60 ₂, and is formulated in accordance with the IPprotocol. Thereafter, the user data sequence is transmitted from each ofthe IP terminals 60 ₁ and 60 ₂ to each of the mobile stations 10 ₁ to 10₃ after it is framed by the use of the PPP RFC 1662 and is furtherframed by the RLP of the radio protocol defined by the IS-707A.

Specifically, the user data sequence is framed into a PPP frame inaccordance with the PPP; RFC (Request For Comment) 1662 and isthereafter further framed into a RLP frame in accordance with the radioprotocol of IS-707A.

It is to be noted here that a transmission rate in the mobilecommunication system is very slow because of an overhead required forradio quality and procedures for establishment/release of connection.Taking this into consideration, the above-mentioned IS-707A includes theRLP type 2 standard of multiplexing a plurality of radio links so as toraise up a transmission rate of each mobile station. Actually, the RLPtype 2 standard serves to improve transmission efficiency and to expandan available bandwidth.

As shown in FIG. 3, the above-mentioned RLP type 2 standard is relatedto radio links or channels between the mobile station (MS) 10 and theradio end terminal 40. The radio links or channels are divided intoforward radio channels from the radio end terminal 40 to the mobilestation (MS) 10 and reverse radio channels from the mobile station (MS)10 to the radio end terminal 40. In the illustrated forward radiochannels, a plurality of the forward radio channels are bundled formultiplexing and are simultaneously established. The plurality of theforward radio channels include a single fundamental radio channel andsupplemental radio channels which may be selectively established fromone to eight.

Such a radio protocol makes it possible to transparently transmit thePPP frame without recognizing the PPP frame and the IP protocol.

On multiplexing the plurality of the radio links or channels, neitherconsideration is made in the above-mentioned radio protocol about thePPP frame nor definition is also made about multiplexing the radiochannels.

Herein, it is to, be noted that the PPP frame is classified into a PPPuser data frame for carrying a user data sequence and a PPP link controlframe for sending an end request, an echo request, and the like. Withthe above-mentioned radio protocol, the PPP link control frame ismultiplexed into the radio channels together with the PPP user dataframe. In other words, the PPP link control frame coexists with the PPPuser data frame in the radio channels.

Therefore, a reception side 10 of the PPP frame can not quickly detectthe PPP link control frame. This means that the PPP link control framecan not be transmitted without any influence to any other radiochannels.

More particularly, it is assumed in FIG. 4 that the BS/MSC/IWF 40 andthe mobile station (MS) have an interworking controller 41 and a radiocontroller 11, respectively, and that a sequence of PPP frames A to F issuccessively transmitted from the interworking controller 41 to theradio controller 11. In the illustrated example, the PPP frame D isassumed to carry an LCP (link control protocol) echo request. Accordingto the above-mentioned radio protocol, each of the PPP frames A to F isdivided into first through fifth pieces of the frames, such as A1 to A5;B1 to B5: C1 to C5; D1 to D5; E1 to E5; and F1 to F5; which aretransmitted through first to fifth ones of the radio channels, asillustrated in FIG. 4. In other words, the radio controller 11 of themobile station (MS) is given first through fifth ones of RLP-framed PPPframes in the illustrated manner.

Under the circumstances, the radio controller 11 of the mobile station(MS) 10 should decode and judge each RLP-framed PPP frame so as todetect the LCP echo request carried by the PPP frame F. Such decodingand judging require complicated processing. This means that sequentialcontrol of the PPP frames should be executed over a plurality of theradio channels. In consequence, processing delays inevitably take placedue to the complicated processing and transmission efficiency isreduced, as mentioned in the preamble of the instant specification.

Referring to FIGS. 5 and 6, a communication system according to apreferred embodiment of this invention comprises a plurality of mobilestations MS1 ₁ to MS1 ₃, a mobile communication network 2 (which may becalled a radio transmission path), an interworking facility 4, and an IPnetwork 5, and a plurality of IP terminals 6 ₁, 6 ₂.The illustratedinterworking facility 4 is operable in a manner somewhat different fromthe radio end terminal 40 illustrated in FIG. 2, as will become clear asthe description proceeds.

The IP terminals 6 ₁ and 6 ₂ may be coupled to the IP network 5 and haveIP interfaces which cany out communication through a network medium,such as Ethernet, ATM (Asynchronous Transfer Mode), or a frame relay.

In the illustrated example, each of the mobile stations MS1 ₁ to MS1 ₃has an interworking controller 11 ₁ to 11 ₃ while the interworkingfacility 4 has an interworking controller 3 which may be similar instructure and operation to each of the interworking controllers 11 ₁ to11 ₃.

In FIG. 5, it is assumed that the interworking controllers 11 may beused as the interworking controller 3, although they can be also used asthe interworking controller 11 in each mobile station MS1 to 3. In thisconnection, each of the interworking controllers 111 to 113 and 3 may becollectively often called an interworking apparatus.

In addition, it is also assumed that the illustrated interworkingcontroller 3 is now assigned five radio channels or links, although thenumber of the radio channels or links may not be restricted to five butcan be changed to any other number, for example, eight or so bynegotiation. At any rate, the interworking controller 3 is given thenumber of the radio channels agreed or consented by the negotiation.

As shown in FIG. 6 the interworking controller 3 has an IP protocolinterface 31 located on the IP network side and a radio interface 36 onthe mobile communication network side. The IP protocol interface 31 isoperable to receive/send an IP packet from/to the IP terminal 6 ₁, 6 ₂,while the radio interface 36 is operable to execute radio protocolinterface processing in accordance with a radio protocol.

Moreover, the IP protocol interface 31 is coupled to a framing portion32 which serves to frame the IP packets into PPP frames. Each PPP frameis successively stored into first through fifth frame memories 331 to335 one by one. In other words, each of the first through the fifthmemories 331 to 335 stores each PPP frame at every PPP frame and may bereferred to as transmitting frame memories.

In addition, the first through fifth frame memories 331 to 335 areconnected to first through fifth RLP (Radio Link Protocol) converters341 to 345, respectively. The first through the fifth RLP converters 341to 345 are operable to convert the PPP frames read out of the PPP framememories 331 to 335 into radio frames in accordance with the RLP,respectively. The converted radio frames are sent from the first throughthe fifth RLP converters 341 to 345 to first through fifth frametransmission portions 351 to 355 and are thereafter transmitted from thefirst through fifth frame transmission portions 351 to 355 through theradio interface 36 to the mobile communication network 20. To this end,the radio interface 36 carries out the radio protocol interfaceprocessing.

Taking the above into consideration, the converters 341 to 345 and theframe transmission portions 351 to 355 may be called a radio frametransmission portion.

Furthermore, the illustrated interworking controller 3 further has firstthrough fifth frame receivers 371 to 375 connected to the radiointerface 36 which are operable to receive radio frames from the mobilecommunication network 20 through the radio interface 36. Such radioframes are received by the interworking controller 3 through firstthrough fifth radio channels or links agreed by the negotiation, asmentioned before. The received radio frames are individually sent tofirst through fifth frame memories 381 to 385 each of which serves tostore the radio frames at every PPP frame and which may therefore becalled RLP frame memories. The radio frames stored in the first throughthe fifth frame memories 381 to 385 are reproduced by a reproductionportion 39 into PPP frames which are sent through the IP protocolinterface 31.

In addition, the interworking controller 3 illustrated in FIG. 5 has areception frame control portion 3A coupled to the framing portion 32 andthe radio interface 36 and a transmission frame control portion 3Bcoupled to the radio interface 36.

Now, operation will be described with reference to FIGS. 5 and 6. Atfirst, let transmission be carried out from the mobile station MS1 tothe IP terminal 6 in the reverse direction. In this event, the mobilestation MS1 negotiates with the radio interface 36 of the interworkingcontroller 3 about the number of forward links or channels and thenumber of reverse links or channels, prior to communicating with theinterworking facility 4. Herein, the forward channels are formed in theforward direction from the interworking facility 4 while the reversechannels are formed in the reverse direction from the mobile station MS1to the interworking facility 4.

As a result of the negotiation, the radio interface 36 of theinterworking facility 4 informs the reception frame control portion 3Aand the transmission frame control portion 3B of the agreed numbers ofthe radio links. Thus, the interworking controller 3 sets the numbers ofthe radio channels and the numbers of both the first through the fifthPPP frame memories 331 to 335 and the first through the fifth RLP framememories 381 to 385 in the illustrated example. Thus, the numbers of theradio channels and/or the frame memories are set as the result ofnegotiation and may be referred to as agreed or accepted numbers.

Under the circumstances, the PPP frame memories 331 to 335 are managedwith reference to the numbers of the radio links in the forwarddirection by the reception frame control portion 3A and store the PPPframes concerned with the corresponding radio channels. On the otherhand, the RLP frame memories 381 to 385 are managed by the transmissionframe control portion 3B of the interworking controller 3 with referenceto the numbers of the radio links in the reverse direction and store theRLP frames concerned with the corresponding radio links.

Now, the PPP frames generated by the mobile station MS1 are framedwithin the mobile station MS1 into the RLP frames and are sent throughthe mobile communication network 2 to the interworking controller 3 ofthe interworking facility 4. In the interworking facility 4, the RLPframes are received through the radio interface 36 of the interworkingcontroller 3 by the first through the fifth frame receivers 371 to 375thereof.

The RLP frames received by the first through the fifth frame receivers371 to 375 are stored in the first through the fifth frame memories 381to 385. It is to be noted here that each RLP frame is given to theinterworking controller 3 at every radio link and may not be separatedor spread into the first through the fifth RLP frame memories 381 to385.

When each of the RLP frames that corresponds to a single one of the PPPframe is stored in every one of the first through the fifth RLP framememories 381 to 385, the transmission frame control portion 3B readseach RLP frame out of the first through the fifth RLP frame memories 381to 385 and sends it to the reproduction portion 39.

The reproduction portion 39 successively receives the RLP frames readout of the frame memories 381 to 385 and reproduces or regenerates thePPP frames. When the PPP frame includes the IP protocol frame, the IPprotocol frame is converted into the IP protocol packet by thereproduction portion 39 to be sent to the IP protocol interface 31. Whenthe PPP frame includes the PPP link control frame, the PPP link controlframe is processed by the transmission frame control portion 3B to besubjected to predetermined processing.

On the other hand, consideration will be made about transmitting the IPprotocol packet from the interworking controller 3 to the mobile stationMS1. In this event, the IP protocol packet is given through the IPprotocol interface 31 to the framing portion 32 and is framed into thePPP frame by the framing portion 32. Each PPP frame is successivelydelivered to the first through the fifth PPP frame memories 331 to 335to be stored therein under control of the reception frame controlportion 3A. Thus, the PPP frame memories are loaded with the PPP frameswhich are made to correspond to the radio channels in number.

In general, the radio interface 36 is slow in speed in comparison withthe IP protocol interface 31. Therefore, the PPP frames should bequickly stored in the PPP frame memories 331 to 335. For example, whenframing operation of the RLP frame is not finished in connection with acertain one of the PPP frame memories, the reception frame controlportion 3A may wait for completion of the RLP frame without any outputoperation.

In addition, the reception frame control portion 3A may give anypriority to each radio link and control an output order of the framesstored in the PPP frame memories 331 to 335, with reference to thepriority.

The first through the fifth RLP converters 341 to 345 are supplied withthe PPP frames from the first through the fifth PPP frame memories 331to 335 and frame them in accordance with the radio protocol into the RLPframes which are dispersed to delivered to the first through the fifthtransmission portions 351 to 355. In this event, each RLP frame is sentfrom the corresponding RLP converter 341 to 345 to the correspondingframe transmission portion 351 to 355 and is supplied to the mobilecommunication network 30. Therefore, controlling the individual RLPframes is not needed in the illustrated example.

In the embodiment according to this invention, when the radio links orchannels are multiplexed in accordance with the radio protocol, theframe memories for storing the frames are set so that they are made tocorrespond to the radio links. With this structure, the radio frames foreach mobile station are sent from the frame memory corresponding to eachradio link or channel. On the other hand, when the radio frame isreceived, the radio frame is stored in the RLP frame memorycorresponding to each radio link and is read out of the RLP framememory. At any rate, each radio link is assigned to the correspondingPPP frame. In other words, the PPP frames is transmitted to thecorresponding radio link at every one of the PPP frames.

As a result, the control frame which may be, for example, the endrequest frame, the echo request frame, and which is defined in the PPPprotocol can be reliably transmitted to the opposite mobile stationwithout any influence to the other radio channels or links. This resultsin dispensing with complex protocol processing, such as sequentialcontrol processing of the PPP frames carried out over the plurality ofthe radio links. Accordingly, it is possible to realize thecommunication system which has a reduced protocol processing delay andimproved transmission efficiency.

While this invention has thus far been described in conjunction with apreferred embodiment thereof, it will readily be possible for thoseskilled in the art to put this invention into practice in various othermanners. For example, this invention is not always restricted to themobile station and the interworking apparatus operable in response tothe PPP frames.

1. A communication system configured to communicate with a mobilestation operable in accordance with a mobile communication protocol anda terminal operable in accordance with an Internet protocol (IP), themobile communication protocol configured to allow use of a plurality ofradio links between the mobile station and the communication system, thecommunication system comprising: framing means for framing received IPframes into point-to-point protocol (PPP) frames; transmifting framememory means assigned to the plurality of radio links for storing thePPP frames, the transmitting frame memory means comprising a pluralityof frame memories which are equal in number to a number of radio linksused to communicate with the mobile station; reception frame controlmeans for assigning the PPP frames generated by the framing means to theplurality of frame memories; and transmitting means for transmitting thestored PPP frames through the plurality of radio links in the form ofthe radio frames.
 2. The communication system of claim 1, wherein themobile communication protocol is a radio link protocol (RLP) and thetransmitting means further comprises: converting means for convertingthe PPP frames stored in the plurality of frame memories into aplurality of RLP frames; and radio frame memory means, corresponding tothe plurality of radio links, for storing the RLP frames.
 3. Thecommunication system of claim 1, further comprising: receiving means forreceiving a plurality of radio frames through the plurality of radiolinks; reception frame memory means for storing the radio frames; andconverting means for converting the radio frames into PPP frames.
 4. Thecommunication system of claim 3, wherein the converting means convertsthe PPP frames to IP frames, the system further comprising: sendingmeans for sending the IP frames to the terminal.
 5. The communicationsystem of claim 3, further comprising: transmission frame control meansfor reading the radio frames out of the reception frame memory means. 6.The communication system of claim 1, wherein the number of the pluralityof the frame memories is configured to change based on the number ofradio links used to communicate with the mobile station.
 7. Thecommunication system of claim 6, wherein the number of radio linksranges from one to eight.
 8. An apparatus, comprising: an Internetprotocol (IP) interface configured to receive and transmit IP frames; aradio interface configured to receive and transmit radio frames; aframer configured to frame received IP frames into point-to-pointprotocol (PPP) frames; a first controller configured to assign thereceived IP frames to one of a plurality of radio links; at least onePPP frame memory configured to store the PPP frames; at least one radiolink protocol (RLP) converter configured to convert the PPP framesstored in the at least one PPP frame memory into RLP frames; at leastone transmitter configured to transmit the RLP frames via the radiointerface; at least one RLP frame memory coupled to the radio interfaceand configured to store the RLP frames received via the radio interface;a second controller configured to read RLP frames out of the at leastone RLP frame memory; and a converter configured to convert the RLPframes read out of the at least one RLP frame memory into IP packets.wherein the apparatus is further configured to: communicate with amobile station to negotiate a first number of radio links from theapparatus to the mobile station.
 9. The apparatus of claim 8, whereinwhen converting the RLP frames read out of the at least one RLP framememory to IP packets, the converter is configured to: convert the RLPframes to PPP frames, and convert the PPP frames to IP packets.
 10. Theapparatus of claim 8, wherein the radio interface is further configuredto: inform the first controller of the first number of radio links. 11.The apparatus of claim 8, wherein the at least one PPP frame memorycorresponds in number to the first number of radio links.
 12. Theapparatus of claim 8, wherein the apparatus is further configured to:communicate with the mobile station to negotiate a second number ofradio links from the mobile station to the apparatus.
 13. The apparatusof claim 12, wherein the radio interface is further configured to:inform the second controller of the second number of radio links. 14.The apparatus of claim 12, wherein the at least one RLP frame memorycorresponds in number to the second number of radio links.
 15. Anapparatus for facilitating communications between a mobile station andan Internet protocol (IP) terminal, comprising: an IP interfaceconfigured to receive and transmit IP packets; a radio interfaceconfigured to receive and transmit radio frames; a plurality of radioframe memories coupled to the radio interface and configured to storethe received radio frames; a first control portion configured to: readthe radio frames out of the radio frame memories, and vary an availablenumber of radio frame memories based on a number of radio links from themobile station to the apparatus; and an IP converter configured toconvert the radio frames read out of the radio frame memories to IPpackets.
 16. The apparatus of claim 15, wherein when converting radioframes to IP packets, the IP converter is configured to: convert theradio frames to point-to-point protocol (PPP) frames, and convert thePPP frames to IP packets.
 17. The apparatus of claim 15, furthercomprising: a framer configured to receive IP packets from the IPinterface and convert the IP packets into point-to-point protocol (PPP)frames; a second control portion configured to assign each PPP frame toone of a plurality of radio links; a plurality of PPP frame memoriesconfigured to store the PPP frames; at least one radio converterconfigured to convert PPP frames stored in the plurality of PPP framememories into radio frames; and at least one transmitter configured totransmit the radio frames via the radio interface.
 18. The apparatus ofclaim 17, wherein the second control portion is further configured tovary an available number of PPP frame memories based on a number ofradio links from the apparatus to the mobile station.
 19. The apparatusof claim 15, wherein the apparatus is configured to: negotiate with themobile station to determine the number of radio links from the apparatusto the mobile station, and negotiate with the mobile station todetermine the number of radio links from the mobile station to theapparatus.
 20. A communication device for use in facilitatingcommunications between a mobile station and a terminal, thecommunication device comprising: a first group of frame memoriescorresponding to a plurality of radio links used to transmit data to themobile station, the first group of frame memories being configured tostore point-to-point (PPP) frames produced from received packets; atleast one radio converter configured to convert the PPP frames stored inthe first group of frame memories into radio frames; a second group offrame memories configured to store radio frames received from the mobilestation via radio links; and a PPP converter configured to convert theradio frames stored in the second group of frame memories into PPPframes.
 21. The communication device of claim 20, wherein the PPPconverter is further configured to convert the PPP frames to Internetprotocol packets.
 22. The communication device of claim 20, wherein thesecond group of frame memories corresponds in number to a number ofradio links used to transmit radio frames by the mobile station to thecommunication device.
 23. In a network device, a method of establishinga connection between a mobile station and a terminal, comprising:storing radio frames received via radio links in radio link protocol(RLP) frame memories, the number of the RLP frame memories correspondingin number to a number of radio links used to transmit the radio framesfrom tbe mobile station to the network device; converting the radioframes into point-to-point (PPP) frames; storing PPP frames receivedfrom the terminal to PPP frame memories, the number of PPP framememories corresponding in number to a number of radio links used totransmit the PPP frames from the network device to the mobile station;and converting the stored PPP frames into radio frames for transmissionvia the radio links.